Effects of Intra-Crystalline Microcracks on the Mechanical Behavior of a Marble under Indentation

Indentation tests have been carried out on a marble in order to define the role of the intra-grain microcracks on its mechanical behavior. The investigated marble shows a strong variability in grain-texture (granoblastic to xenoblastic) also on the scale of centimeter and contains different types of microdiscontinuities (cleavage cracks, grain boundaries cracks), despite the almost monomineralic composition of calcite crystals. The mechanical properties of the calcite grains have been determined by applying static non-instrumented Vickers and Knoop indentations and Berkovich nanoindentation in Continuous Stiffness Measurements (CSM) mode. The study has clearly revealed the influence of microcracks on the mechanical strength and deformability characteristics of the investigated rock, even on the smallest scales.